A smart watch is a wrist watch employed with an embedded system for enhanced functions based on time reporting, and has functions similar to a personal digital assistant (PDA). An early stage smart watch is able to perform basic functions of calculating, translating or consoling handheld electronic games, and a mid-term smart watch has realized a function of a wearable computer. Most smart watches are able to execute mobile software applications, some of them may run a mobile operation system (OS), and a few of them have a full mobile phone function. Other functions mainly relate to portable multimedia play, such as playing FM radio and message or movie files and listening through Bluetooth earphones.
Apple Inc. released Apple Watch in the fourth quarter of 2014, while its most major flaw is the serious shortage of power supply that requires an instantly charging within a continuous use of less than 24 hours. A wearable smart product itself is limited to its finite volume, and the battery accommodating space is reduced and limited while pursuing a large display area. Accordingly, it is a major research direction in the future to solve the power supply problem of a wearable smart product.
Some current available smart watch absorbs sunlight and generates electric power by adding a solar cell plate on the watch dial. However, during a daily use, the watch will turn to various directions with the wrist, and thus it cannot ensure that watch dial always faces the light source. Accordingly, the obtained electric power is limited, which makes little help to the battery life.